If a prop is feathered and an engine is shut down, will the engine
windmill at all?

I assume that a windmilling prop still turns the engine (i.e., no
clutch disconnects it from the engine, at least on a piston
powerplant). If so, can windmilling drive an alternator enough to
provide useful electrical power?

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Mxsmanic wrote:
> If a prop is feathered and an engine is shut down, will the engine
> windmill at all?
>
> I assume that a windmilling prop still turns the engine (i.e., no
> clutch disconnects it from the engine, at least on a piston
> powerplant). If so, can windmilling drive an alternator enough to
> provide useful electrical power?
>
You'll never know until you get into a plane. A real plane. Re: your
question... Some will. Some won't. Again, stop cross posting. At best,
you're a student. At worst, you're not even human.

Rip

Do you know the difference between a windmilling prop and one that is
feathered? Try looking this up first before wasting more electrons.

Rip writes:

> You'll never know until you get into a plane.

Oh, I think someone who knows the answer will eventually tell me. I
have to put up with a bit of background noise, but there are still a
few qualified and sensible people on these newsgroups.

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Viperdoc writes:

> Do you know the difference between a windmilling prop and one that is
> feathered?

Yes. I also know that not all props have adjustable pitch, and that
the fully feathered position on a prop will not necessarily be exactly
parallel to the wind.

I suppose the question can apply to jet engines as well, but someone I
doubt that they would windmill with speed sufficient to generate
useful power, and I'm not sure which stage of the engine drives
generators, anyway.

Obviously windmilling itself is practical, since some aircraft have a
tiny deployable windmill specifically for this purpose.

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On Feb 6, 7:53 pm, Mxsmanic > wrote:
> Yes. I also know that not all props have adjustable pitch, and that
> the fully feathered position on a prop will not necessarily be exactly
> parallel to the wind.

Sorry everyone but I am gonna feed the troll here.Most of the props
that I have seen fethered are actually feathered enough to stop or
spin very slowly.
>
> I suppose the question can apply to jet engines as well, but someone I
> doubt that they would windmill with speed sufficient to generate
> useful power, and I'm not sure which stage of the engine drives
> generators, anyway.

Not sure what you are asking here, but a jet engine will not
feather .The fan blades are not adjustable.The compressor section
drives the generator, but it will not spin fast enough to generate
electricity (Even with a CSD).What is interesting is that it will
indicate oil pressure and with this indication (And the absence of
vibration) a restart is recomended.
>
> Obviously windmilling itself is practical, since some aircraft have a
> tiny deployable windmill specifically for this purpose.

All of the ER versions of 2 engine transport category jets have this
function.
>
> --
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Sorry about feeding the troll guys, but he ask a question that I
actually knew something about.

>
>
> What is interesting is that
it will
> indicate oil pressure and with this indication (And the absence of
> vibration) a restart is recomended.
>

That is interesting and usefull, although I'll never personally have
any occasion to use it.

On 2007-02-07, Mxsmanic > wrote:
> If a prop is feathered and an engine is shut down, will the engine
> windmill at all?
>
> I assume that a windmilling prop still turns the engine (i.e., no
> clutch disconnects it from the engine, at least on a piston
> powerplant). If so, can windmilling drive an alternator enough to
> provide useful electrical power?

With piston engines, when the prop is feathered (hence blades are more
nearly parallel with the wind) there is usually enough compression in the
engine to prevent the blades from turning. This might also depend upon how
completely the blades feathered.

So even if the prop turned at all there would not be enough rotation for the
alternator to be of any use. Also, in an emergency all electrics may be
turned off anyway to prevent fire hazards.

With turboprop engines there are two types. Engines like Garretts have the
props connected by planetary gears to a shaft and both the compressor and
exhaust turbine blades are connected to the same shaft with no breaks in the
shaft. Accessories, such as starter/generators and other pumps are connected
to this via gears. This is called a fixed shaft turbine.

My experience is with a Commander 840 with -10 Garretts and when the props
are feathered there is a very slow turning of the props, but not enough to
effect any generation of current.

The second type of turboprop would be like the Pratts where the prop is
free-wheeling (free turbine) and the connection to the actual engine is via
two sets of blades positioned in front of each other, one set on the shaft
to the engine and the other set to the prop. I'm not as familiar with this
engine, but whether or not the prop rotated, it isn't connected to
accessories anyway so of no use.

Remember than when an engine is shut down in flight, whether intentional or
not, all electrical to the engine might be shut down, including any fuel
pumps, generators, etc., (and usually is) in handling the emergency to
prevent other problems, such as fire.

....Edwin
--
__________________________________________________ __________
"Once you have flown, you will walk the earth with your eyes
turned skyward, for there you have been, there you long to
return."-da Vinci http://bellsouthpwp2.net/e/d/edwinljohnson

Edwin Johnson writes:

> With piston engines, when the prop is feathered (hence blades are more
> nearly parallel with the wind) there is usually enough compression in the
> engine to prevent the blades from turning. This might also depend upon how
> completely the blades feathered.
>
> So even if the prop turned at all there would not be enough rotation for the
> alternator to be of any use. Also, in an emergency all electrics may be
> turned off anyway to prevent fire hazards.
>
> With turboprop engines there are two types. Engines like Garretts have the
> props connected by planetary gears to a shaft and both the compressor and
> exhaust turbine blades are connected to the same shaft with no breaks in the
> shaft. Accessories, such as starter/generators and other pumps are connected
> to this via gears. This is called a fixed shaft turbine.
>
> My experience is with a Commander 840 with -10 Garretts and when the props
> are feathered there is a very slow turning of the props, but not enough to
> effect any generation of current.
>
> The second type of turboprop would be like the Pratts where the prop is
> free-wheeling (free turbine) and the connection to the actual engine is via
> two sets of blades positioned in front of each other, one set on the shaft
> to the engine and the other set to the prop. I'm not as familiar with this
> engine, but whether or not the prop rotated, it isn't connected to
> accessories anyway so of no use.
>
> Remember than when an engine is shut down in flight, whether intentional or
> not, all electrical to the engine might be shut down, including any fuel
> pumps, generators, etc., (and usually is) in handling the emergency to
> prevent other problems, such as fire.

Thanks for the detailed answers. It is interesting that some turboprops don't
have a solid connection to the prop--it seems that this could come in handy if
the prop is blocked or hits something, as it might help preserve the engine
(with no solid connection, the engine would not be violently immobilized).

It has also been pointed out to me (in e-mail) that the question is a bit moot
because: (1) if you have a twin, the other engine is presumably still running,
so you don't need the electricity that might hypothetically be generated by
the alternator on the dead engine, and (2) if you have a single, you'll
probably be on the ground before the battery goes dead, one way or another.
This would be true for both jets and props, of course.

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Hash: SHA1

An imposter of "Mxsmanic" writes:

> Thanks for the detailed answers. It is interesting that some people
> continue answering my stupid questions.
>
> How about dancing for me too.

You need to use correct punctuation if you wish to be believable. Also, I
have a fairly consistent style to my writing that you fail to emulate.

It seems odd to me that the very people who complain about my posts here
would double the apparent traffic from them by pretending to be me. Perhaps
Ms. Nowak has peers on this newsgroup.


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On Wed, 07 Feb 2007 17:34:15 +0100, Mxsmanic wrote:

> if you have a single, you'll
> probably be on the ground before the battery goes dead, one way or another.

Why on the ground one way or another? A prop single can fly all day with a
dead battery and alternator.
--
Dallas

Dallas writes:

> Why on the ground one way or another? A prop single can fly all day with a
> dead battery and alternator.

Not if the engine isn't running. If the propeller is windmilling, presumably
the engine is dead.

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"Mxsmanic" > wrote in message
...
<...>
> It seems odd to me that the very people who complain about my posts here
> would double the apparent traffic from them by pretending to be me.
> Perhaps
> Ms. Nowak has peers on this newsgroup.
>

You, sir, owe Ms. Nowak an apology for compairing her to the scum sucking
trolls that have infested this group.

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

Don't fall for this. MS is impersonating himself -- what a wonderful
scam!

..

On Feb 7, 5:08 pm, "Capt. Geoffrey Thorpe" <The Sea Hawk at wow way
d0t com> wrote:
> "Mxsmanic" > wrote in message
>
> ...
> <...>
>
> > It seems odd to me that the very people who complain about my posts here
> > would double the apparent traffic from them by pretending to be me.
> > Perhaps
> > Ms. Nowak has peers on this newsgroup.
>
> You, sir, owe Ms. Nowak an apology for compairing her to the scum sucking
> trolls that have infested this group.
>
> --
> Geoff
> The Sea Hawk at Wow Way d0t Com
> remove spaces and make the obvious substitutions to reply by mail
> When immigration is outlawed, only outlaws will immigrate.

On Feb 7, 12:00 pm, Mxsmanic > wrote:
> It seems odd to me that the very people who complain about my posts here
> would double the apparent traffic from them by pretending to be me. Perhaps
> Ms. Nowak has peers on this newsgroup.

The fakes are easy to spot. They include this line from the dizom
anonymous remailer:

Mail-To-News-Contact:

To get rid of them, you need to contact dizum and tell them your email
is being misused:

"Dizum FAQ [13] Q: What is your policy on forgery?

"A: We have a policy against a user of Dizum making posts in a way
that uses the email address of another user on Usenet or the Internet,
in an attempt to deceive readers of the true identity of the poster,
without that email address owner's permission. In addition, if you are
the victim or witness to a forgery, you may want to contact the
appropriate law enforcement agency so they may then contact us and
follow-up as they feel appropriate. If you feel that your email
address is being forged and you do not want to make use of the Dizum
mail2news gateway nor the Dizum remailer we can add that address to
the blockfile. This will disable any postings with that from line. "

Kev writes:

> The fakes are easy to spot. They include this line from the dizom
> anonymous remailer:
>
> Mail-To-News-Contact:
>
> To get rid of them, you need to contact dizum and tell them your email
> is being misused:

Hmm ... now who here would know about anonymous remailers?

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Nomen Nescio writes:

> -----BEGIN PGP SIGNATURE-----
> Version: N/A
>
> iQCVAwUBRcrCopMoscYxZNI5AQE0DQP8D/NnWzDoO3w+kI1zs+oerCqWOB/4/00o
> OEqyFe19cKfLry4Wj8hmgtRhV6NhXWkitCbzJjtrNxzNaq0sOC GmUlZxgR0JIETx
> LxWZH3JmeMuOCOjbzmx5VAk2nCfHNDYXsvPnI0unz6XlVTOXCb qo9ppS4CN8nYsg
> RtrV/6hjvj0=
> =JFlx
> -----END PGP SIGNATURE-----

Where is your public key? It's not on the standard servers.

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Mxsmanic writes:

> Gee. I hope they don't verify that the address is really mine.
> That wouldn't work too well.

It's easy to forge a sending address, but it's impossible to
simulate intelligence, so I do have that working in my favor.


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=PwxV
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Nomen Nescio writes:

> I've posted it a couple of times, here.
> Check the dashes at the beginning and end of the block. Sometimes (don't
> know why) it goes through with a dash & space added (- -----) when it should be
> (-----). Just delete the dash & space before adding it to your ring.
> Then, of course, check it against a previous post to verify that it came
> from me.

Well, actually I was hoping for a separate source for the key. A public key
posted in a USENET post isn't very useful for verifying a USENET post, since
it's not an out-of-band source.

In my case, my public key is on my Web site, so anyone can download it and at
least be sure that whoever signs my USENET messages also controls my domain
and Web server, which is a pretty good indication that I am who I claim to be.

I think my public key is also on a couple of servers, but I'm not sure (the
servers themselves don't always strike me as very stable).

> It's always a good idea to put a PGP sig on your posts. Headers can
> be forged. But if someone is duplicating a PGP sig.......They're probably
> NSA.

Signing things that don't need to be signed is an unnecessary security risk.

> I had someone try to impersonate me on another group about 6 months
> ago. The idiot copied my PGP sig from another post I made. When I
> exposed the fraud, someone else verified that the sig was corrupt and
> that the post was a forgery. Once you put your sig on something, every
> word, sentence, space, and comma is set in stone and tied to you, alone.

Yup.

> Did you file a complaint with Dizum M2N, yet?

No. I'm not convinced that it's that big a deal. People who are smart enough
to care about whether or not it's really me are also smart enough to spot
impersonations--just the style of writing alone gives it away. And those who
aren't smart enough don't matter.

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